[PAN-2560] Cleanup PeerConnection interface

[mbaxter]

PR description

Small cleanup to the PeerConnection interface:

• Keep local / remote addresses as InetSocketAddress values
• Add getEnode method, remove isRemoteEnode since this can be checked directly now
• Rename getPeer to getPeerInfo

[shemnon]

Is this always an InetStocketAddress in the manner we use netty? Are there other things it could be, that we might actually use?

[mbaxter]

According to the docs on SocketAddress:

This class represents a Socket Address with no protocol attachment. As an abstract class, it is meant to be subclassed with a specific, protocol dependent, implementation.

And InetSocketAddress:

This class implements an IP Socket Address (IP address + port number)

I think the change makes sense.

We were casting it all over the place assuming it was an InetSocketAddress anyway and I think its better to just be explicit.

[mbaxter]

Also, InetSocketAddress is actually the only subclass of SocketAddress

[mbaxter]

I actually think we could probably just get rid of these methods. I'll try to do that.

[shemnon]

It would localize where the cast is in the unlikely case it's ever a problem. But if we can get rid of the methods entirely that is also less code, which is generally better.